Gelatinized dynamite containing polyvinyl butyral resin and method of producing same



United States Patent US. Cl. 149-50 16 Claims ABSTRACT OF THE DISCLOSURE A gelatinized dynamite in which the nitroglycerin content is reduced to about 8 to 16% by weight by blending a gel of polyvinyl butyral resin in a solvent, such as caster oil, dibutyl phthalate or dioctyl phthalate, and polyoxyethylene stearate, with a known constituent, such as nitroglycerin or nitrocellulose, and which nevertheless has excellent detonation ability plasticity and extrudability The present invention relates to gelatinized dynamites in which the content of nitroglycerin (or a mixture of the same with nitroglycol, which will hereinafter be referred to as nitroglycerin for simplicity) is reduced to about 8 to 16% by weight and which nevertheless have an excellent detonation ability and are sufiiciently shapable into cartridge by conventional extruder type or rollentype cartridging machine, and a process for the production thereof.

The plasticity and extrudability of conventional gelatin dynamites depended upon the amount of nitro gel consisting of nitroglycerin and nitrocotton, and the minimum amount of the nitro gel, which provides for extruding of the resultant gelatin dynamites, has been about 30% by weight. However, there has been a desire for reducing the amount of nitroglycerin blended in gelatin dynamites to a minimum, due to the facts that it is expensive and that nitroglycol admixed in nitroglycerin is poisonous for human body. Recently, an auxiliary plasticizer, such as aromatic nitro compound, surface active agent or synthetic resin, have been used for the purpose of reducing the amount of nitroglycerin to below the aforementioned minimum limit, but even in this case an amount of nitroglycerin as much as 18% by weight is the practical minimum limit. The amount below the said limit results in drastic deterioration of the plasticity and extrudability of dynamites. Even if the product dynamite is shapable, it tends to be hardened with the passage of time, with the result that the detonation ability thereof is deteriorated, making the dynamite unserviceable for practical applications. The use of such auxiliary plasticizer in a large amount to avoid such undesirable effect, however, will cause various drawbacks. That is, the use of an aromatic nitro compound in a large amount will result in lowering the sensitivity of explosive and also in separation of and exuding a liquid substance, whereas the use of a surface active agent in a large amount will render the explosive excessively soft, so that the explosive cannot retain its shape and therefore handling of the explosive, during production, storage and use, becomes inconvenient. On the other hand, when a synthetic resin is used in an excessively large amount, the detonation property of the explosive is extremely deteriorated and the capability of sympathetic detonation of the explosive is lowered remarkably. Due to the foregoing reasons, only the use of auxiliary plasticizer in a large amount has not been very much effective in reducing the amount of nitroglycerin.

The object of the present invention is to provide a gelatinized dynamite in which the amount of nitroglycerin is reduced to about 8 to 16% by weight by blending a gel of polyvinyl butyral resin in such a solvent as castor oil, dibutyl phthalate (hereinafter referred to as DBP) or dioctyl phthalate (hereinafter referred to as DOP), and poyloxyethylene stearate, a non-ionic surface active agent, with a conventional constituent, such as nitroglycerin or nitrocellulose, and which nevertheless has a good detonation ability, plasticity and extrudability stands up satisfactory in long storage.

Polyvinyl butyral resin is more combustible than other plastics such as vinyl chloride-vinyl acetate copolymer, vinyl furfural and vinyl alcohol, and a gel thereof is highly suitable for use as an auxiliary plasticizer in the production of gelatinized dynamites, because of its excellent adhesion and spinnability. Polyvinyl butyral resin is a white powder and must therefore be dissolved in a solvent before it is used as an auxiliary plasticizer. Although this resin is a polyfunctional resin having in its molecule a butyral group, acetyl group and hydroxyl group, and is soluble in many volatile solvents, the use of volatile solvent in gelation of the resin will result in deterioration of the explosive during production process and storage of the product, as a result of evaporation of the solvent from the gel, causing hardening of the dynamite. For this reason, polyvinyl butyral resin must be dissolved in a nonvolatile solvent.

The present inventors have evaluated various types of non-volatile solvents and found that castor oil, DBP and DOP are suitable as a solvent for polyvinyl butyral resin. The viscosity of the resultant resin gel is highest when castor oil is used and, for a given concentration, the viscosities of the gels obtained by the use of the remaining two solvents are and respectively of the former. Therefore, in order to obtain a gel of polyvinyl butyral resin having the same viscosity as that obtainable by the use of castor oil, using the latter solvent, a larger amount of polyvinyl butyral resin should be dissolved therein. Other non-drying vegetable oils such as olive oil and camellia seed oil which are similar to castor oil, are not capable of dissolving the resin. Castor oil is triglyceride of ricinoleic acid and contains about 90% of ricinoleic acid Which has one hydroxyl group. A polyvinyl butyral resin which is most easy-soluble in castor oil, DBP or DOP, is the one which has an average polymerization degree of 700 to 800 and contains at least 67 mol percent of butyral group and 4 to 6 mol percent of residual acetyl group. The use of polyvinyl butyral resins having an average polymerization degree lower than that specified above will result in lower viscosity of the resultant gel, whereas the use of polyvinyl butyral resins having an average polymerization degree higher than that specified will result in lower solution velocity. On the other hand, polyvinyl butyral resins containing not more than 67 mol percent of butyral group are hard-soluble in the solvents. A practically suitable solution velocity of polyvinyl butyral resin in a viscous solvent having such a large molecular Weight, can be obtained when the particle size of the resin passes through 28 meshes of the Tyler standard sieve.

A gel of polyvinyl resin in castor oil DBP or DOP is characterized by the fact that it is miscible with nitro gel in any proportion to produce a homogeneous gel which is durable for storage over a prolonged period and temperature variation, without causing separation of and exuding nitroglycerin, castor oil, DBP or DOP therefrom. However, an explosive having a sufiicient sensitivity cannot be obtained by merely blending the resin gel with other constituents. In general, sensitivity of explosive has a close relation with the amount of fine air bubbles enclosed therein, and the more the air bubbles are, the higher the sensitivity of the explosive will be.

3 In this respect, polyoxyethylene stearate, which is a nonionic surface active agent, has the property of producing a number of fine air bubbles in the gel and therefore is effective not only in reducing the surface tension and enhancing the powder covering ability of the gel, but also 4 having a diameter of 8 mm., a length of 50 mm. and a penetration angle of 60 was dropped spontaneously on a horizontally positioned sample dynamie from a point 36 mm. above said sample dynamite under a total load of 50 g., and the penetration depth thus formed was in improving the plasticity, extrudability and detonation measured 3 seconds later. Extrudability is unsatisfactory ability of the resultant explosive remarkably, in combinawhen the penetration depth is 4 mm. or smaller (too hard) tion with said foaming effect. or 9 mm. or greater (too soft), satisfactory when it is From the foregoing description, it will be understood in the range from 5 to 7 mm., and most satisfactory when that an auxiliary plasticizer to be used in the present 10 it is 6 mm. invention is most preferably composed of a polyvinyl W t t butyral resin; castor oil, DBP or DOP as a solvent for a erqesls ance said resin; and polyoxyethylene stearate as a surface A sample of known weight is dipped in water (20:2" active agent. The polyoxyethylene stearate, which has a C.) for 2 hours and, after removing the water-impregmelting point of 35 C. and therefore is in the state of nated portion, the weight of non-impregnated portion is wax at room temperature, is preferably added with O to measured. Water-resistance is represented by the formula: 50% by weight of polyoxyethylene nonylphenol ether, so water resismnce= as to lower the meltmg point and thereby to render it easy-soluble in the solvent. The addition of more than WW 50% by weight of polyoxyethylene nonylphenol ether Original total Weight 0 causes the foaming effect of the surface active agent to A value f 90% or hi h i d d excellent, 90 to bc descfeased, With the consequent increase of bulk 70% satisfactory and 70% or below unsatisfactory. sity of dynamite, lowering of sympathetic detonation degree, lowering of the viscosity and degradation of shapa- Hardness after storage bility of the product explosive. The term polyoxyethyl- This property is represented by b/aX 100, wherein a ene stearate as used hereinafter will include those which is the hardness of a dynamite measured by penetrometer are added with polyoxyethylene nonylphenol ether as deimmediately after production and b is the hardness of the scribed above. same measured one month later. The smaller the value is,

The polyoxyethylene stearate is mlxed with and dis the greater the hardness. A value of 75% or greater is solved in a resin gel at the ratio of one or more parts of satisfactory. the former per one part of the latter, said resin gel con- H b sisting of not more than 20% of polyvinyl butyral resin 65s Same and not less than 80% of castor oil, DBP or DOP. The 50 g. of dynamite is detonated on the top of two lead resin gel is preferably used in an amount from 0.1 to cylinders supported on a heavy iron base. The shortening 2% by weight of the product dynamite. The use of the of the cylinders is taken as a measure of the brisance. The resin gel in an amount less than 0.1% will result in poor test is conducted in accordance with Die Schiess und shapability of the product explosive, whereas the use Sprengstoife p. 365 (1933) by A. Stettbacher. of the resin gel in an amount more than 2% will result Sample No. 1 in Example 1 was produced in the folin lowering of the sensitivity of the same, rendering the lowing manner. An auxiliary plasticizer was first of all explosive unserviceable. Polyoxyethylene stearate is prefprepared by charging 445 parts of castor oil in a mixer, erably used in an amount from 0.1 to 2% by weight of adding 5 parts of polyvinyl butyral resin, elevating the the product dynamite. The use of polyoxyethylene stearate temperature to C. with stirring, dissolving the mixin an amount less than 0.1% will result in poor detonature over one hour, adding 50 parts of polyoxyethylene tion ability of the product explosive, whereas the use of the stearate (containing 25% by weight of polyoxyethylene same in an amount more than 2% will result in lower- 45 nonylphenol ether) to be dissolved therein, and then aling of the viscosity of resin gel or nitro gel and the lowing the resultant mixture to cool to room temperature product explosive presents a semi-gelatinized state having to give an easy-handling plasticizer. In this case, the a poor shapability. handling of the auxiliary plasticizer is rendered much easy EXAMPLE 1 No. 1, No. 2 No. 3 N0. 4, No.5, No. 6, N0. 7 No. 8, percent percent percent percent percent percent percent percent Composition:

NitroglyceriIL- Nitrocotton Dinitro componn Ammonium nitrate.

DOP

Polyoxyethylene stearate (conta g 25% by weight of polyoxyethylene nonylphenol ether) Polyoxyethylene nonylphenol ether-formalin condensate...

Ethanolamine oleate 1 Excellent. 2 Satisfactory. 3 Unsatisfactory.

NOTES: TESTING METHOD Extrudability This property is represented by the value of penetraby lowering the viscosity thereof. Then, ammonium nitrate, starch, dinitro compound, nitro gel and the auxiliary plasticizer prepared in the manner described were charged into a mixer with planetary motion in the pretion test using a penetrometer. A stainless steel needle 75 scribed amounts respectively and kneaded for about twelve minutes. The resultant mixture was extruded and packaged by an extruder type cartridging machine to produce a gelatinized dynamite.

Samples Nos. 1, 2 and 3 were produced using polyoxyethylene nonylphenol ether formaline condensate and ethanolamine oleate respectively in lieu of polyoxyethylene stearate in Sample No. 1. Samples Nos. 4 and 5 were produced using DBP and DOP respectively in lieu of castor oil in Sample 1. Sample No. 7 was produced in the same manner as Sample No. 1 but without using the resin gel, whereas Sample No. 8 was produced in the same manner as Sample No. 1 but without using the resin gel and the surface active agent, Samples No. 7 and No. 8 being reference samples.

Sample No. 1 according to the present invention exhibited a suitable extrudability, less hardening after storage and excellent water-resistance and Hess brisance. Samples No. 4 and No. 5 also showed satisfactory properties. In contrast, Sample No. 2 showed a strong tendency of hardening because the polyoxyethylene nonylphenol ether-formaline condensate has a strong aflinity with water and a poor solubility in castor oil. Sample No. 3 was unsatisfactory in that the ethanolamine as an active agent has a poor aflinity with castor oil, producing no foam at all, and it has a heavy bulk density, alike Sample No. 8 which contains no effective plasticizer. Sample No. 6 was inferior to Samples No. 1, No. 4 and No. 5 because no active agent was used. Sample No. 7 was too soft to retain its shape because no resin gel was used. As can be seen from the foregoing, Samples No. 1, No. 4 and No. 5, according to the present invention, are much superior to the other samples.

far as compared with Sample No. 6. Sample No. 3, which contained only 12% of nitroglycerin, had properties equivalent to those of Sample No. 7 which is a conventional dynamite containing as much as 22.5% of nitroglycerin. Samples No. 1 and N0. 2, which contained 16% and 14% of nitroglycerin respectively, showed highly excellent properties, proving the remarkable elfect of the unique auxiliary plasticizer.

We claim:

1. In a gelatinized dynamite, the improvement comprising the inclusion in said dynamite of (A) from about 0.1% to about 2% by weight of a gel of polyvinyl butyral resin in a solvent selected from the group consisting of castor oil, dibutyl phthalate a nd dioctyl phthalate; and

(B) from about 0.1% to about 2% by weight of a member selected from the group consisting of:

(1) polyoxyethylene stearate and,

(2) mixtures of not less than about 50% by weight polyoxyethylene stearate and not more than 50% by weight polyoxyethylene nonylphenol ether.

2. The gelatinized dynamite of claim 1 in which said gel comprises not more than about 20% by weight of said polyvinyl butyral resin and not less than about 80% by weight of said solvent.

3. The gelatinized dynamite of claim 2 which contains about 0.1% to about 2% by weight of said polyoxyethylene stearate.

4. The gelatinized dynamite of claim 2 in which said solvent is castor oil.

Present Invention Reference Standard Example- Explosive- No. 1, No. 2, No. 3, No. 4, No. 5, No. percent percent percent percent percent Composition:

Nitroglycerine 16. 0 14. 0 12. 0 10.0 8.0 N itrocotton 0. 7 0.7 0.6 0. 5 0. 4 Auxiliary plastieizer 1. 6 0. 8 0. 09 0 1. 2 1. 5 Polyvinyl butyral 0. 06 0. 03 0. 03 035 0. 04 Castor oil 0. 54 0. 27 0. 27 0.315 0. 36 Polyoxyethylene stearate 0 5 0. 6 0. 85 1. 10 Diniro compound 2. 0 4. 7 5. 1 5. 4 5. 4 Starch 5. 2 4. 3 4. 0 3. 5 3. 2 Ammonium nitrate 74. 5 75. 5 77. 4 79. 4 81. 5 Properties:

Extrudability Bulk density of dynamite (g./cc.) 1. 1 25 1. 25 1. l0 1. 10 Gap test on sand (mm.); immediately after productiom-cartndge diameter mm.) 210 150 100 80 0 90 Three months after produetion0artridge diameter (30 mm.) 150 120 80 50 30 0 Detonation velocity (m./s.); In open state (cartridge dlameter 30 1 Excellent. I Unsatisfactory.

NOTES: GAP TEST ON SAND A semicircular groove having the same diameter as the cartridge is formed in sand and two cartridges are placed in said groove with an interval therebetween. The first cartridge is initiated using No. 6 detonator and then the second cartridge is exploded completely. The maximum detonable distance between the ends of the cartridges is measured.

Detonation velocity The detonation velocity is measured using a detonating fuse whose detonation velocity is known. The test is conducted in accordance with The Chemistry of Powder and Explosives page 17 (1950), by Tenney L. Davis.

The samples used in Example 2 were produced in the same manner as Sample No. 1 in Example 1. Samples No. 1 to No. 5 are of the present invention and were easy-extrudable into cartridges. Sample No. 6, in which the unique auxiliary plasticizer was not used, presented a semi-gelatinized state and could not be extruded into cartridge. Samples No. 1 to No. 5 according to the pres ent invention demonstrated on excellent detonation ability and even Sample No. 5, which contained a very small amount, i.e. 8%, of nitroglycerin, was satisfactory by 5. The gelatinized dynamite of claim 2 in which said dynamite comprises not more than about 16% by weight of a member selected from the group consisting of:

( 1) nitroglycerin and (2)mixtures of nitroglycerin and nitroglycol,

6. The gelatinized dynamite of claim 2 in which said dynamite contains not less than about 8% by weight of a member selected from the group consisting of:

(1) nitroglycerin and (2) mixtures of nitroglycerin and nitroglycol.

7. A gelatinized dynamite composition comprising:

(A) nitrocellulose, a dinitro compound, ammonium nitrate, an inert filler,

(B) not more than about 16% by weight of a member selected from the group consisting of (1) nitroglycerin and (2) mixtures of nitroglycerin and nitroglycol, (C) a plasticiser comprising from 0.1 to 2% by weight of a gel of polyvinyl butyral resin dissolved in a solvent selected from the group consisting of castor oil, dibutyl phthalate, and dioctyl phthalate, and (D) from 0.1% to 2% by weight of a surface active agent selected from the group consisting of:

(1) polyoxyethylene stearate and (2) mixtures of polyoxyethylene stearate with less than about 50% by weight of polyoxyethylene nonylphenol ether.

8. The gelatinized dynamite of claim 7 in which said gel comprises not more than about 20% by weight of said polyvinyl butyral resin and not less than about 80% by weight of said solvent.

9. The gelatinized dynamite of claim 8 in which said solvent is castor oil.

10. The gelatinized dynamite of claim 8 in which said surface active agent is a mixture of polyoxyethylene stearate with less than about 50% by weight of polyoxyethylene nonylphenol ether.

11. The gelatinized dynamite of claim 8 which comprises not less than about 8% by Weight of said member selected from the group consisting of:

(1) nitroglycerin and (2) mixtures of nitroglycerin and nitroglycol.

12. In a process for producing a gelatinized dynamite, the improvement comprising:

(A) dissolving polyvinyl butyral resin in a solvent selected from the group consisting of castor oil, dibutyl phthalate and dioctyl phthalate to produce a resin gel,

(B) admixing 0.1% to 2% by weight, based on the total weight of said dynamite, of said resin gel with 0.1% to 2% by weight, based on the total weight of said dynamite, of a member selected from the group consisting of:

(1) polyoxyethylene stearate and (2) mixtures of not less than 50% by weight polyoxyethylene stearate with not more than about 50% by weight polyoxyethylene nonylphenol ether, and

(C) kneading the resultant mixture with an explosive composition to form a gelatinous dynamite.

13. The process of claim 12 in which said resin gel comprises not more than about 20% by weight of said polyvinyl butyral resin and not less than about by weight of said solvent.

14. The process of claim 13 in which said solvent is castor oil.

15. The process of claim 13 in which said polyvinyl butyral resin has a particle size sufficiently fine to pass through 28 mesh of Tyler standard sieve.

16. The process of claim 13 in which said gelatinized dynamite composition contains from about 8% by weight to about 16% by weight of a member selected from the group consisting of:

(1) nitroglyerin and (2) mixtures of nitroglycerin and nitroglycol.

References Cited UNITED STATES PATENTS 234,489 11/1880 Morse 149101 649,852 5/1900 Luck 149101 1,838,345 12/1931 Woodbridge 149101 X 3,018,201 1/1962 Downard 149101 X BENJAMIN R. PADGETT, Primary Examiner.

S. I. LE-CHERT, Assistant Examiner.

US. or. X.R. 

